This is the "shareholder value" theory, modern economists successfully brainwashed the population with. It became popular during the 1980s, "greed is good" times. It's just an ideology disguised as a science. The purpose and structure of modern corporation hasn't changed in the last hundred years or so. In 1950s and 1960s the public good, among others, role of corporations was wildly accepted. What changed is the ideologues who became more vicious and took complete control of the narrative.